The disclosure relates to a regulating valve which is provided, in particular, for the electroproportional regulation of the pivot angle on a hydraulic machine as a swashplate type and which has the features according to the disclosure. The disclosure relates, moreover, to a hydraulic system having a regulating valve of this kind.
DE 10 2008 035 133 A1 discloses a regulating valve of this kind for a hydraulic axial-piston variable-displacement pump. The regulating valve is part of an actuating device for adjusting a stroke volume of the variable-displacement pump. The actuating device engages on a pivoting rocker of the variable-displacement pump by means of a swing-in piston of a swing-in cylinder and by means of a swing-out piston of a swing-out cylinder. The variable-displacement pump can be adjusted via the swing-in piston in the direction of a lower delivery volume and via the swing-out piston in the direction of a higher delivery volume. To swing out the pivoting rocker, the swing-out piston can be acted upon with a pressure medium via an actuating pressure space, as result of which an actuating pressure can act on this swing-out piston. The swing-in piston can likewise be acted upon with a pressure medium via an actuating pressure space in order to swing-in for the pivoting rocker. The actuating pressure for the swing-in piston is regulated via the regulating valve.
The continuously adjustable regulating piston of the regulating valve is acted upon via a first valve spring with a spring force in the direction of regulating positions in which the actuating pressure space of the swing-in piston is connected to the high-pressure side of the variable-displacement pump. The regulating piston can be acted upon in the opposite direction with a spring force of a second valve spring, the spring force being adjustable. Action upon the regulating piston by the second valve spring then takes place in the direction of regulating positions in which the actuating pressure space of the swing-in piston is connected to the tank. The delivery pressure acts on the regulating piston via a lever device counter to the spring force of the second valve spring. The lever device is a hyperbolic controller, via which the regulating piston of the regulating valve can then be activated as a function of the delivery pressure of the variable-displacement pump.
The applicant's data sheet RD 92800/05.12 discloses a further embodiment of a regulating valve on a variable-displacement pump. The regulating valve is in this case part of a power controller. According to the above-explained embodiment of DE 10 2008 035 133 A1, a regulating piston of the regulating valve can be acted upon by spring forces of two counter acting valve springs. The second valve spring, here too, is configured in such a way that one spring force is adjustable. The delivery pressure of the variable-displacement pump likewise acts counter to the spring force of the second valve spring via a lever device. Furthermore, the regulating piston of the regulating valve is constantly displaceable in the active direction of the first valve spring via a lifting magnet, that is to say into regulating positions in which the actuating pressure space of the swing-in piston is connected fluidically to a high-pressure side of the variable-displacement pump.
A lifting magnet for adjusting the regulating piston of the regulating valve is illustrated in DE 199 52 800 A1. This has a magnet armature which is guided slidably in a pole tube and by means of which it can displace an armature tappet, while the latter, in turn, can engage on the regulating piston of the above-explained regulating valve. The first valve spring of the above-explained regulating valve can be supported on a spring plate of the lifting magnet. Said spring plate is supported, in turn, on a pin, arranged in the magnet housing, of an adjusting device, via which the spring plate can be displaced axially in order to set the spring force of the first valve spring.
DE 10 2008 038 435 A1 shows a further embodiment of a regulating valve. In this case, the regulating piston can be displaced in the direction of first regulating positions, in which the actuating pressure space of the swing-in piston is connected fluidically to the tank, and in the direction of second regulating positions, in which the actuating pressure space is connectable to the high-pressure side of the variable-displacement pump. The regulating piston can be acted upon in the direction of the first regulating positions by the magnetic force of a first lifting magnet and by the spring force of a valve spring. The regulating piston can be acted upon in the direction of the second regulating positions by a spring force of a feedback spring and by a magnetic force of a further lifting magnet. The spring force of the valve spring which acts in the direction of the first regulating positions can be adjusted via an adjusting device. The valve spring is in this case supported on a spring plate, of which the side pointing away from the valve spring has a frustoconical configuration. A pin engages on the frustoconical side, which pin is inserted radially to the longitudinal axis of the regulating piston in a valve housing of the regulating valve and can be displaced in its axial direction. If, for example, the pin is displaced toward the spring plate, the pin slides along the frustoconical side of the spring plate, with the result that the latter is displaced in the direction of an increasing spring force of the valve spring. If the pin is adjusted in the opposite direction, it slides outward, radially away from the regulating piston, along the frustoconical side of the spring plate, with result that the spring plate is displaced in the direction of a decreasing spring force of the valve spring. The pin is fixed and secured to the valve housing via a lock nut. In the regulating valve, the adjustable spring force of the spring acts on the regulating piston in the same direction as the magnetic force of the first lifting magnet.
By contrast, the object on which the disclosure is based is to provide a regulating valve having a simple configuration in terms of apparatus and a hydraulic system having a regulating valve of this kind.